"I got out this morning at 8:30 am. My husband and my daughter came to collect me," Ni, who has been confined to a wheelchair since sustaining serious injuries during an earlier stint in jail, said.
"Right now I'm in a very poor state of health because on top of the injuries I suffered when I was tortured before going to prison, I'm suffering from thyroid cancer and a lymphoma behind my left ear," said Ni, who is in her 50s.
In July last year, a court cut Ni's sentence to 30 months in jail after overturning a fraud conviction, but rejected her appeal against the charge of "picking quarrels", her lawyer Cheng Hai said.
The court also rejected an appeal against Ni's husband Dong Jiqin's conviction and two year jail sentence on the same charge.
More From This Section
Lawyers for Ni and her husband have said all along that the charges were trumped up to silence the rights defender.
She and her husband were detained in April 2011 as China rounded up hundreds of activists amid calls for protests akin to the Arab Spring popular revolts that erupted across the Middle East.
Her sentencing in April last year sparked an international outcry, and the United States and European Union both called for her release.
Trained as a lawyer, Ni began providing legal aid to residents facing home demolitions after her own courtyard home in central Beijing was requisitioned in 2001.
The next year she was sentenced to one year in jail for "obstructing official business" and disbarred as a lawyer.
After her release she was confined to a wheelchair, which the rights group Amnesty International blamed on abuse while in prison.
After a brief period of freedom in 2010, police relocated her and her husband to a hotel and later requested them to pay the 69,000 yuan (USD 11,000) bill, which they refused to do.